Wide mouth volumetric flasks are calibrated to Class A tolerances and are designed for microchemical work. Low actinic stained glass provides protection for materials sensitive to light. The protective color is an integral part of the flask, which retains its mechanical strength, chemical stability and thermal resistance. The heavy duty, wide mouth facilitates filling and mixing. Supplied with an interchangeable No. 16 Standard Taper PYREX* ground glass stopper. For replacement stoppers, see No. 7650. The graduation line is sharp and permanent.